Should is used to give advice or to talk about what you think is right or wrong.
You should do something = It is the right thing to do something, or it is a good thing to do something.
SUBJECT + SHOULD + VERB BASE FORM
– Mark is getting asleep at work. He should sleep better.
– Peter looks tired. He should go to bed.
– Star Wars is a great movie. You should see it.
– Should I tell her the bad news?
You shouldn´t do something = it is not a good thing to do.
SUBJECT + SHOULD NOT (SHOULDN´T) + VERB BASE FORM
We use shouldn’t to advise not to do something, usually because it is wrong.
– Brad shouldn´t eat pizza if he wants to lose weight.
– Kate watch YouTube videos all the time. She shouldn´t spend so much time on YouTube.
– Shouldn´t you inform him of the price increase?
I think… should…. ( I think is a good idea…)
– I think Mary should leave that job.
– I think I should practice my conversation skills.
Another way to say should is ought to.
Ought to sounds more formal than should and is used less frequently.
– I think Robert ought to buy new shoes.
– You ought to study more.